“We would become a $16.2 billion agency,” Bolden said during a hearing of the Senate Appropriations commerce, justice, science subcommittee. “Right now, we’re operating at $16.8 [billion] and we would go down to $16.2 [billion] in 2014.”

Sequestration phased in March 1 and, according to Bolden’s figures, took a $1 billion bite out of NASA’s 2013 budget — a 5.6 percent cut compared with 2012 levels. The 2013 budget was finalized March 26 when the Full-Year Continuing Appropriations Act of 2013 (H.R. 933) was signed.

The White House is seeking $17.7 billion for NASA under the 2014 budget request unveiled April 10. President Barack Obama’s budget request ignores the effect of sequestration, a series of across-the-board cuts intended to reduce federal spending by about $1 trillion over 10 years.

The White House and Congress have wrangled over NASA’s top-priority programs, but the list since 2011 has been the Space Launch System (SLS) heavy-lift rocket, the Orion Multi-Purpose Crew Vehicle, the James Webb Space Telescope (JWST), and commercial crew and cargo transportation to the international space station.

SLS’s maiden flight, in which it will carry an empty Orion to lunar space, is set for 2017 — the same year at least one of the three private companies subsidized by NASA to build crew transportation vehicles is due to fly astronauts to the space station for the first time. The long-delayed JWST, a technically ambitious infrared successor to the visible-spectrum Hubble Space Telescope, is slated to launch in 2018.

But if sequestration continues through 2014, “it will potentially impact JWST, it will definitely impact SLS [and Orion], it will devastate commercial crew and cargo,” Bolden said. Moreover, “I will, in all probability, have to furlough civil servants.”

Back in March, Bolden told attendees of the Goddard Memorial Symposium in Greenbelt, Md., that NASA had avoided civil servant furloughs in 2013 by assuming sequestration would hit March 1, and aligning its spending with the projected cuts. Contractor layoffs also figured into the agency’s sequestration plans, although NASA has not quantified the reduction to that portion of its work force.

“I’ll have to renegotiate those contracts,” Bolden said. “We’re flying 20 commercial cargo missions to the international space station over the next five years [and] I can’t carry that out under sequester.”

It is not certain when or if the White House and Congress, which could not agree on a deficit reduction plan last year, might get around to replacing sequestration with more narrowly targeted spending cuts.

Meanwhile, before Mikulski arrived at the hearing to question Bolden about the toll sequestration would exact on NASA in 2014, the subcommittee’s new ranking member, Sen. Richard Shelby (R-Ala.), grilled Bolden about SLS and Orion — programs for which NASA is seeking less funding in 2014 than it received for 2013.

Shelby is a staunch, outspoken defender of the Marshall Space Flight Center in Huntsville, Ala., which is managing the SLS project. He is also deeply skeptical about the commercial crew and cargo programs.

“Based on the proposed budgets, as well as previous budgets, I have serious doubts about NASA’s dedication to truly developing a heavy launch capability,” Shelby told Bolden. The 2014 budget request “shows cuts to [Space Launch System] vehicle development, as far as we can see. This budget focuses, I believe, too heavily on maintaining the fiction of privately funded commercial launch vehicles, which diverts, I think, critical resources from NASA’s goal of developing human spaceflight capabilities with the SLS.”

Bolden maintained that SLS is “on schedule, on target and on cost” for its 2017 debut, and for a follow-on flight in 2021, in which the rocket will launch astronauts for the first time.

The White House requested a total of $2.7 billion for SLS and Orion for 2014 — about what it sought in 2013, but roughly $115 million less than the projects stand to receive under the omnibus spending bill signed March 26.

Since 2007, NASA has devoted just over $4.5 billion to cargo delivery and technology development contracts for SpaceX and Orbital. SpaceX already has flown two cargo delivery and return missions to the space station, the latest in March. Orbital, meanwhile, launched its Antares rocket for the first time April 21, clearing the way for that company’s own demonstration delivery mission to the space station this summer.

The Commercial Crew Program, which NASA started in 2009 to foster a U.S. alternative to paying Russia $65 million a seat for astronaut rides to the international space station, has garnered just $1.5 billion of NASA’s budget to date.

SLS, Orion and their associated ground systems, meanwhile, cost NASA about $2.7 billion a year. These vehicles, however, are capable of going much farther from Earth than the space station delivery vehicles NASA has subsidized. SLS and Orion have both been designed with an eye toward taking astronauts to Mars.